1. Field
The present embodiments relate to in-vehicle knob switch device, which is also known as a stalk switch. In particular, the present embodiments relate to an in-vehicle knob switch device having a pushable operating knob disposed on an outer periphery surface of a tubular housing.
2. Related Art
In a typical vehicle, an in-vehicle knob switch device, known as a stalk switch, is disposed near a steering column and is provided for controlling, for example, wipers and headlights. An in-vehicle knob switch device generally includes, for example, a tubular housing tiltably supported by the steering column. An operating knob is exposed through an opening provided in an outer periphery surface of the housing. A holder is fixed inside the housing. A circuit board is supported by the holder. The circuit board has, for example, a push switch disposed thereon, which is actuated when the operating knob is pushed. A user can tilt the housing or push the operating knob to turn a wiper device on or off, to adjust the intensity level of the wiper device, to change intermittent modes of the wiper device, to turn the headlights on or off, or to change beam modes of the headlights.
As a known example of such an in-vehicle knob switch device, Japanese Unexamined Patent Application Publication No. 10-269898 (pages 3 and 4, FIGS. 1 and 2) discloses a device having a housing that has a guide member disposed therein, which supports the operating knob in a vertically movable fashion. The guide member is combined with the holder using fixing means of, for example, a snap-fit type, and the push switch mounted on the circuit board is embraced by the guide member. The guide member is provided with a cylindrical guide portion at a position facing the push switch. A columnar boss protruding from an undersurface of the operating knob is slidably engaged with the guide portion so that the operating knob can be pushed smoothly.
In an in-vehicle knob switch device of this type, if an internal space of the housing is dimensionally reduced due to, for example, limitations in design, it is difficult to attain a space for setting the guide member mentioned in the above-reference conventional example. Therefore, the guide member has to be omitted, which implies that the operating knob must be guided with the housing itself. In that case, a guide portion extending inward towards the surface of the circuit board may be provided around the opening of the housing, and the guide portion may serve as a slide surface for guiding the operating knob vertically. Because the housing has disposed therein the holder that supports the circuit board, the maximum permissible length of the guide portion is limited to within a distance between the opening and the holder. This may be problematic in that a large backlash may occur in the operating knob during a pushing operation.